Electric heater.



W. s. ANDREWS'.

ELECTRIC HEATER.

APPLICATION FILED .TUNE 12, 1908.

Patented 00t.28,1913.

Fig. 5.

Inventor: Wil Ham S. f!

Witnesses:

ers., of which the following is. a. specification.4

TEnsTATEs PATENT ortica.

WILLIAM S. ANDmS, @Y SmBG'IDY, NIW mx, ASSIGNBRTOJ GENERAL EBBM'MANY, A CORPGILTIOH OB'NEW TUBE..

' 4 mueren: Huren.

Loveseat of Letters Patent..

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To all whom L may. concerns.

Be it known that 1?,.WILLIAM a citizen ost the United.i States, residir at Schenectady county of Schenectady, tate of Sew: York, have invented certainY new and. useful Improvements in Electric Heat- This invention. relates to electric heaters, and has for its object the provision. of a device of thischaracter which may be raised to-a 'relatively hl h temperature without deterioration, whc will be. simple and cheap to. construct, and. at the same time be. reliablee efficient and durable.

One of the objects' of my invention is to produce an electric heating device provided with a protective and insulating covering which is infusible at any ordinary high temperature, and. which at the Sametime will retain its insulatin properties and will not be aieoted by sud n. changes in temperature; I have found that fused silica is very well suited for this purpose. In certain methods of cooking, suchfor instance as broiling and toasting, radiant heat is necessary in order to produce the best results. This radiant heat is usually supplied in electric heating devices from as heating resistance generally consisting of'a bare Wire or other material which is brought up-to a high temperature by the passage of an electric current. This use of. a bare conductor is dangerous and unhygienic. By placing the conductor Within a protecting envelop or tubefof used silica, the above noted defects are entirely avoided, and the silica becomes incandescent and radiates heat abundantly. By reason of its high fusing point'the silica may be brought to a much higher temperature than is ever required for cooking without suieringan'y injury or becoming softened in the slightest degree. This material is moreover a perfect insulator, and unlike glass or enamels retainsV its insulating properties when raised toa high temperature.

VIt cannot be oxidized or injured by heat or moisture nor is itv affected by acids other than hydro'luoric. Furthermore it does not appreciably change its volume under wide ranges of temperature. 'This last-named 1property permits it to 3be plunged while -red ot into cold waterfw'it-hout cracking. In this respect it diiers'entirely from glass and all kinds of enamel. The commercial material is moreover semi-transparent, thus en-4 S. AnD-Ruwe@ -abling a person to determine by the eye the.

temperature which is reached.

In the accompanying drawing in which I have.. shown my invention embodied in a number of concrete forms Figure l is a. View. partlyY in section of an' Vimmersion vheater;l*"ig. 21 isa section thereof; Fig. 3 is fa perspective view of a toaster embodying' my invention;v Fig.. 4 is a detail, ofthe support for the tubes for the toaster; andV Iig.4

. isfan annealing furnace for wire.

Referring. to the drawing (Figs. 1 and- 2), 104 is aresistance conductor spirally wound upon a. tube or refractory material, such as itube 11 of fused silica. One terminal' is brought back through the tube and connect' ed 4with a plug connection 152; the other terminal being connected' to the screwed part of the plug connection, the heating unit being thus adapted for connectionto electr-ic circuit through a socket. A tube 13 of `:t'usedA Asilica or the like surrounds the resistance spiral and has one end sealed' over andi the other secured, to lug 12 so as to. completely protect the con uctor. preferably of high electrica-l resistance, is heat refractory to an extraordinary degree,l and does not readily orridizevvhensubjected to a prolonged red hea/t in the atmosphere. It has a melt-ing point between 1400 and 1500 degrees centigrade. Such a conductor is disclosed in the patent to J. T. H; Dempster, No. 901,428. The'resistance may become red hot and heat will be transmitted to the tube 13 which in turn will become incandescent. This tube may then be used as an immersion heater and ,plunged into water.

In Fig. 3 I have' shown another use of my invention. In this case a plurality of tubes This conductor is SQ 15 are mounted side by side on insulating blocks 16. These blocks are set upon a frame 17 and supported on legs in a Wellknown manner. V.Ai screen 18 is arranged t0 cover the tubes and be out of Contact with them as shown. In this Way the radiant heat of the tubes will be transmitted to the food to be toasted or broiled. g A convenient mounted upon a tub 22, which tube in turn is mounted within a fused silica tube 23, and supported therein by sealing the ends 24, and the wire 25 which is to be annealed runs thro-ugh the tube as shown.

- `Various other uses and applications of my invention will suggest themselves to those skilled in the art, and while I have Shown my invention embodied in a number of concrete forms, it should be understood that I do not limit my invention thereto eX- cept in so far as it is limited by the scope of the claims annexed hereto. What I claim a s new and desire to secure by Letters Patent of the United States, is' l. In an electric heater, the combination of a quartz covering, and a continuous metallic heating resistance of greater lengththan said covering located inside the same and having a melting point lower than the melting point of said covering whereby said resistance may be raised to a temperature above its glowing point without endanger-a`- ing said covering, substantially as described.

2. In an' electric heater, the combination of a quartz covering, a continuous metallic heating resistance of greater length than. said covering located inside the same and having a melting point lower than the melting point of said covering whereby said resistance may be raised to a temperature above itsglowing-point without endangerling lsvaid covering, and means for connecting vcovering and a continuous metallic heating resistance of greater length than said covering mounted upon sa-id support, the melting said resistance to a source of current, subpoint of the said heating resistance beinglower than the melting point of the covering .whereby said resistance may be raised to a temperature above its glowing point without endangering said covering.

4:. In an elect-ric heater, the combination of a closed quartz covering, a support sealed within said covering and a metallic heating v resistance of greater length than saidcovering mounted upon said, support and having a melting point lower than that of said covering whereby.y said resistance may be raised to a temperature above its glowing point without endangering said covering.

5. In an electric heater, the combination tube, and a continuous metallic heating resistance wound upon the sald rod and having a melting point lower than that of said tube whereby said resistance may be raised to a temperature above its glowing point Without endangering s'aid tube.

In witness whereof, I have hereunto set my hand this 11th day of June, 1908.

'of a quartz tube, a'quartz rod within said 

